10 ECU Extremadura

The ECU — European Currency Unit — was never legal tender in Spain or anywhere else; it existed purely as a basket currency used for accounting within the European Monetary System. Spain's regional ECU series, issued through the early 1990s, exploited a deliberate gray area: the coins were technically denominated in a unit that had no cash circulation, allowing commemorative issues to carry face values without competing with peseta coinage. Extremadura's inclusion honored the region's outsized role in the conquest of the Americas, given that Cortés, Pizarro, and de Soto all hailed from its territory.